CA1340259C - Process and apparatus for performing chemical reactions under pressure in a multi-staged reaction zone with intermediate external thermal conditionning - Google Patents

Abstract

The invention relates to a method and an apparatus for carrying out chemical reactions under pressure in the presence of a solid catalyst in a multi-stage reaction zone with external intermediate thermal conditioning. The purpose of this process can be the synthesis of ammonia, methanol or the reforming of gasolines. The method is characterized in that at least one reaction fluid is introduced into at least one compartment, a first reaction effluent is recovered, a heat exchange outside the reaction zone between the first effluent and a medium external heat exchange, this first effluent is then introduced into at least one subsequent compartment and a second reaction effluent is recovered from the subsequent compartment. In addition, the reaction fluid or the reaction effluent is circulated in the compartments transversely in a manner substantially perpendicular to the generator of the reaction zone, the compartments being sealed and of elongated shape, each of the compartments being adjacent to one or two others. compartments, each group of two adjacent compartments comprising a common or common wall either substantially parallel to said generator, or substantially oblique to said generator.

Description

The invention relates to a method for performing under pressure chemical reactions from reaction fluids in the presence of at minus a solid catalyst, in a multi-stage reaction zone with external intermediate thermal conditioning. It relates to also the reactor for the implementation of the process and the use reactor and process.

The invention is particularly applicable to the synthesis of methanol, am-moniac as well as catalytic reforming, stabilized hydrogenation I0 gasoline satrix and hydrocracking of heavy petroleum cuts.

More generally, it is applicable in all heterogeneous catalysis processes where fluid reactants, either liquid or gaseous, either the liquid and the other gaseous are brought to react between them, in a succession of several catalytic beds constituted by grains, granules, spheres or other solid elements with structures more or less complex and elaborate.

The reactions concerned generally occur with heat reaction requiring one or more thermal readjustments intermediaries with the external environment.

When you want to carry out chemical reactions at high heat of reaction, it is known to do it in several stages with a rajus-thermal intermediate after each of them.

Thus, in the catalytic reforming of gasolines for example (patent FR 2 160 269 - US 4 210 519 - US 4 233 268), we generally have three solid catalyst bed reactors separated by two ovens for external heating.

This multiplicity of reactors is costly in equipment, piping and implantation space.

This is the reason why it has often been proposed to group the different reactors into a single reaction vessel ~ e of which .... ", .. .. ~

134025g the walls are calculated to be able to withstand internal pressure well relatively high system.

In this solution, the solid catalyst beds are superimposed vertically and rest either on support grids or directly on horizontal partitions. (FR-A-2.573.996).

These grids and partitions must support, on the one hand the weight of the bed catalytic, on the other hand from the constraints arising from the pressure drop due to the circulation of the reaction fluid through the equipment heat transfer and the catalytic bed itself.

It results from the addition of these two constraints, loads extremely 15 high, of the order of 50 to 100 and even 150 tonnes per square meter then that current specifications for industrial floors are limited around 0.5 to 1 ton per square meter.

To avoid this cumulative effort which leads to mechanical solutions restrictive both from the point of view of the weight of the support beams that of the lost dead space, it has been proposed, in particular for methanol reactors (Hydrocarbon Processing, May 1984 p 95-100) a superposition, no longer of axial reactors, but of reactors radials where, the catalyst being placed in a cylindrical cartridge hollow, or even in several cartridges, the reaction fluid circulates horizontally either centrifugally from the inner cylinder to outer cylinder or centripetal way of the outer cylinder towards the inner cylinder.

This solution which has the advantage of unloading the separation floors, stress loads due to the circulation of the reaction fluid, has the drawback of leaving a lot of dead space, in particular an empty central core that GB patent 1140071 teaches to fill with a heat exchanger.

A drawback of this solution, underlined by US patent 4225562 .. ..... ..

1 ~ 0259 results from the difficulty of correctly centering the two cylinders delimiting the solid catalyst crown. This decentralization results in hetero-unfairness in the course of flowing nets, extremely harmful to the successful completion of the basic reaction and which leads to thermal exceedances endangering the stability of the catalyst.

Another disadvantage is the obligation to load and unload management of catalytic cartridges. For this purpose, we can install flanges of the same diameter as that of the reactor but this solution is not not the best when operating under pressure and the size of the reactor is important. It is then recommended to weld the ends generally hemispherical to the cylindrical body but to perform the unloading the catalyst, it is necessary to saw each time the say ends to remove the cartridges and resolder them after the reactor loading phase. The operation is long, delicate, subject each time to an administrative authorization and control.

In addition, US Patent 4,225,562 teaches to provide compartments parallelepipedal arranged parallel to the axis of the enclosure and having all the same section and the same volume.

The device makes the best use of half of the available space. Besides the mechanical complexity and therefore the high cost of the device, the standard distribution of identical volume compartments prohibits the adaptation of the catalytic volume at the variation of the reaction rate. Thereby, the patent can only apply to reactors or to a single kinetic stage only speaking be realizing reactions whose speed does not vary as a function of the conversion, that is to say reactions of zero order.

13gO2. ~ 9 Regarding the different variants of bulkhead reactors radial, the device taught by US Pat. No. 3,898,049 can be mentioned, where the catalytic cartridge is divided into several sectors in the longitudinal direction. These sectors are successively traversed by reaction fluids, alternately from top to bottom and from bottom to top along the longitudinal axis of the reaction vessel. It is easy to realize that the proposed device is only applicable in very special cases where the length of the course and, by way of As a result, the pressure drops are of little importance because, compared to an axial reactor of the same height, and a fortiori compared to a reactor radial, the fluid path is considerably lengthened and proportional the number of sections in the cartridge.
Furthermore, the prior art is illustrated by patent GB 2,120,119 which 15 describes a longitudinal reactor for carrying out syntheses chemical in the gas phase. This reactor includes enclosures parallelepipedic containing catalyst arranged along the axis of the reactor and having permeable opposite walls through which the charge circulates. The effluent can be internally cooled by a 20 quench, which limits the internal available space.

Patent FR-A-2,573,996 also illustrates a catalytic reactor with single compartment for the synthesis of ammonia and methanol without internal exchangers and whose wall temperature is maintained at 25 a low level by the presence of an air mattress.

Finally, patent DE-A-2,929,300 describes an exchanger reactor with axial flow in catalytic zones of variable section, these zones being non-adjacent.

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13 ~ 0259 One of the first objects of the invention is therefore to propose a process and a multi-stage reactor, under pressure with external intermediate thermal conditioning, which do not have the disadvantages mentioned above.
In particular, an object of the invention is to propose a inexpensive reactor that is easy to build and easy handling for loading and unloading of the catalyst.

Another object is the realization of a reactor where substantially all of the available volume can be occupied by the catalyst.

Yet another object of the invention is to be able to ensure better control of the speed distribution of the fluid through the catalytic beds so as to avoid local overheating, which would be sure to turn off the catalyst and therefore reduce its useful life and disrupt the progress of the reaction.
According to the present invention, there is therefore provided a method to carry out chemical reactions under pressure in a cylindrical reaction zone based on a circular section laire comprising at least two compartments, a first and a second, each containing at least in part at least a solid catalyst, process in which a reaction fluid in the first compartment, we do circulating said reaction fluid in said first compar-we recover a first reaction effluent from said first compartment, heat is exchanged outside of the reaction zone between said first effluent reaction to enter the second compartment and an external heat exchange medium, then we introduce B

., I34 ~ 259 said first effluent having exchanged heat in said second compartment, said first is circulated effluent in said second compartment and a desired mixture, said reaction zone being shaped elongated and comprising an envelope with at least one generator, said envelope defining a closed section lying in a plane intersecting said generator, method in which:
- circulating said reaction fluid in said first compartment transversely and so substantially perpendicular to said generator, and we circulates said first reaction effluent through said second compartment transversely and fa ~ on substantially perpendicular to said generator, - said compartments being of elongated shape according to said generator and being waterproof, - said compartments being adjacent to each other, and - said compartments forming a group having a wall which is connected in fa ~ on tight to said envelope.

Preferably, said reaction fluid comprises hydrogen and carbon monoxide.

Preferably, the reaction zone comprises more than two compartments, each of the compartments is adjacent to one or more two compartments, and each group of two compartments adjacent having a common or party wall which is connected fa ~ on tight to said envelope.
In a preferred embodiment, the reaction zone it has three compartments, and B

- when circulating said first effluent in said second compartment we recover it in the form of a second reaction effluent from said second compartment, and - after having reconditioned said second effluent reaction outside the reaction zone to a optimal temperature we reintroduce it in a third compartment from which it is permanently recovered from the lower part of the reaction zone, in the form of lo the desired mixture.

Under these conditions the reactor presents a good compromise filling and pressure drop level and more allows the fluid has regular paths in the bed catalytic.

Instead of a continually oblique party wall, the reactor may have a wall comprising sections offset from each other in the same direction, each of them being parallel to the generator, but the whole of which constitutes the equivalent of a wall oblique.

All of these wall sections are interconnected so as to be fluid tight. This characteristic has the advantage of varying the thickness of the bed catalytic in the reactor to improve distribution fluid in the catalytic mass over its entire height.

The length of each compartment and each wall joint is substantially that of the reaction zone and the sectional section of the compartments can be inscribed substantially in the section of the envelope.

All compartments are hydrodynamically isolated and waterproof so that there is no communication possible between the various compartments inside the area reaction by any wall whatsoever. The fluid or the reaction effluent usually enters a compartment by an entrance connected to a distribution inside and out of the compartment having crossed the entire catalytic bed transversely, by an exit connected to an indoor collection area generally located opposite the distribution area.

The number of compartments and therefore exchanges of intermediate heat is variable depending on the case cash. The section and / or volume of the compartments can be the same or different and is advantageously determined according to the parameters and constraints of the process to perform, for example the reaction rate which is a function of the degree of progress of the conversion.

The invention also relates to the device for setting process work.

According to the present invention, there is also provided a apparatus for carrying out reactions under pressure chemicals including:
- an elongated reactor capable of containing at least minus a catalyst, having a substantial envelope-cylindrical defined by at least one generator and having a first end and a second end 'waterproof, - at least two adjacent compartments, contained in said elongated reactor along said generator, each group of two adjacent compartments comprising a U ~

134 ~ 2. ~ 3 8a dividing or common wall, each compartment comprising in addition at least one means for entering the reaction fluid or of the reaction effluent in said compartment and at minus a means of leaving the reaction effluent which has passed through said compartment, said means of entry and outlet being in communication with the outside of the reactor through said envelope, characterized in that:
- said compartments are waterproof, said wall adjoining or common being either substantially parallel to the generator is substantially oblique to it and in this that the reactor includes:
- at least one means of distribution in each compartment suitable for distributing t ~ ansversely in each compartment for reaction fluid or reaction effluent substantially perpendicular to said generator and connected to said input means, - at least one means of collecting the reaction effluent circulating in each compartment, this means of collection being connected to said outlet means of said compartment, and - at least one means of heat transfer located ~ to the outside of the reactor interposed between said means of outlet of the reaction effluent from one of the compartments and the means of entry of the reaction effluent into the next compartment.
another means of heat transfer or exchange consi ~ te according to another embodiment, to be carried out by mixing 3 using gas and advantageously fluid or effluent cool and relatively cold reaction, at a cooling of the effluent at its outlet of at least one compartment and before it is sent to a next compartment this mistletoe has the advantage of removing one or more exchangers. To this end, the reactor generally presents ~ means of introduction of this gas to achieve this quenching (or "guench") these means can be inside or outside the reactor and preferably outside.
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_ - 8b -The reaction zone or enclosure of the reactor, shaped elongated, is generally divided, in the direction of the length, advantageously in a direction substantially parallel to the generator, in several compartments, by watertight bulkheads, which can be connected directly to the enclosure envelope. The length of the partitions waterproof according to the generator is generally equal to the length of the reactor.

The compartments thus defined, previously filled with solid catalyst, are successively traversed by the reaction fluid which is either a gas or a liquid or a gas-liquid mixture.

The fluid and more precisely the reaction effluent, after having partially reacted on the catalytic bed of a /
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I3402 ~ 9 of the enclosure, passes through a heat transfer device which recondition at the correct temperature and re-enter the enclosure to go to the next catalytic stage. The volume of each compartment is generally adjusted so that in each compartment the temperature variation between the inlet and the outlet of the compartment between about 1 and 200 ~ C and preferably between 5 and 150 ~ C.

This path of the fluid generates pressure losses and creates pressure differences between the adjoining compartments of the enclosure.
These dynamic pressure differences exert on the walls of the compartments, mechanical stresses which can be considerable and which can result in metal thicknesses with difficulty acceptable.

The dividing walls of the different compartments can be either supported flat panels, vertical or oblique, preferably curved, self-supporting panels. They can be advantageous-ment, substantially parallel to the generator of the reaction zone.

When the panels are flat and supported, preferably the supports are tie rods placed substantially perpendicular to the planes of the panels and connected on the one hand to the partition, on the other hand to the wall of the reaction chamber.

When the panels are self-supporting, preferably they contain either assemblies of profiled sheets or sectors cylindrical whose generatrices are substantially parallel to the generator of the reactor and whose bases are either arcs of a circle whose radius is between 0.1 and 100 times, preferably between 0.5 and 50 times that of the reaction vessel, i.e. portions of quadratic curves such as parabola, hyperbola or ellipse.

Inside the compartments filled with solid catalyst elements, the reaction fluid or the reaction effluent is introduced and distributed through the catalytic mass, by means of distributors constituting the distribution area.

The fluid nets thus formed, after having passed through the catalytic bed, ... . ... ...

are collected and brought to the exit using general collectors opposite the distributors, which constitute the area of collection.

Distributors and collectors are arranged in such a way that the reaction fluid (and the effluent) does not flow in the direction longitudinal of the reaction zone, which lengthens and increases considerably the flow of fluids as well as the pressure losses resulting but transversely perpendicular to the axis of the cylinder forming the enclosure. The total path of the fluid through the catalytic beds can usually stay less than twice the length L, from tangent to tangent of the envelope or of the cylindrical wall dric of the reaction zone, preferably less than or equal to one times this same length L. (See fig 16 defined below).
For this purpose, distributors and collectors can be constituted by pipes whose sections are either circles, sectors of circle, polygon or plane be still sections commonly referred to as "scallops". The area of the sections may vary along the generator as a function of the flow of fluid passing to it level.

The pipes can either be parallel to the generator of the reactor or oblique to this generator.
The means of entry and exit of the reaction fluid or effluent can be placed anywhere on each compartment. They can however, be advantageously located in such a way that the means are located substantially at one of the two ends reactor (or compartment) and the outlet means are located substantially at the other end. According to this embodiment, the section of the distribution pipes at the entrance to the compartment is advantageously greater than that of the same distribution pipe to the other end of compartment due to higher gas flows at the inlet level and vice versa the section of the collection pipe is ......

advantageously smaller at this entry because of the more low gas flows collected at this same level, as that of the same pipe at the outlet end of the compartment.

This arrangement makes it possible to maintain a substantially constant speed.
gas at any point in the distributor and manifold, which also allows optimize the filling of the compartment with catalyst.

To achieve this objective, according to a particular embodiment, the wall of the distributor and collector can include on the parts facing the catalytic bed or at least one distribution section and collection (a grid for example) substantially parallel to the general ratrice, i.e. at least one sensitive distribution and collection section obliquely oblique to said generator, each of these sections distribution and collection being shifted in the same direction, one relative to each other so that the fluids pass through a thickness of constant catalytic bed.

The number of distributors can be greater or less than the number of collectors. Preferably, the number of distributors is the same as the number of collectors, which allows a good distribution of the gas flow When there are a large number of distributors and collectors in a compartment reduced, equal to or less than three, they can be arranged against the enclosure wall near the junctions between the enclosure wall and party walls. This solution is particularly interesting for process low flow rates and is very simple to implement. The circulation of the reaction fluid and effluent is then substantially parallel to the party walls.
Preferably, when distributors or collectors are in number equal to or greater than four, they are distributed along the walls adjoining and where appropriate on the parts of the enclosure wall facing these same party walls. This arrangement allows treat large flow rates of reaction fluid and effluent. It im-poses a circulation of the reaction fluid and effluent in a sensitive manner slightly perpendicular to the watertight dividing walls of the compartments 134 ~ 259 To distribute or collect the reaction fluid, the distributors and collectors can either be drilled with holes or consist of grids comprising openings formed from metallic wires, either crossed or parallel and whose profiles can be studied to facilitate the flow of fluid.

In certain compartments, the average distance of a fluid net of a distributor to a collector, or distance between distributor and collector may be the same from one distributor to another, but this average journey of a fluid net can be variable from one distributor to another.

Preferably, the opening section on the catalytic bed of the distributor and collector facing it is variable depending of the length of the average route connecting these elements, i.e. to the distance distributor-collector facing it.

These various characteristics as well as other elements making part of the invention are described more fully in the description which follows.

According to one embodiment, the reaction fluid and the effluents can circulate in a manner substantially parallel to the party wall which delimits two adjacent compartments, which is advantageous when the catalyst volumes in the various compartments are substantially of the same order.

According to another embodiment of the method, the circulation can take place substantially perpendicular to said wall, in particular ment when the distributors or collectors are located on this wall.

This embodiment is particularly advantageous when the catalyst volumes in the different compartments are very different.

The speed of the fluids in the compartments is generally understood between 1 and 200 m / s and preferably between 5 m / s and l00 m / s and depends of course on the reaction and the operating conditions chosen.

.. ~. ... ... ~.

13 13 ~ 02.59 The temperature of the fluids in the various compartments is generally Lement between 100 and 800 ~ C, preferably between 200 and 600 ~ C.

The invention will be better understood and the advantages will appear clearly in view of the examples and the various figures schematically illustrating the apparatus and the process without limitation, including:

- Figures la, lb, 1c and ld show embodiments different from the process and from the reactor according to the invention, - Figures 2, 3, 4, 5 and 6 show different types of walls watertight terraced, - Figures 7, 8, 9, 10, 11, 12 and 13 illustrate different types distributors and collectors and different modes of circulation fluid and reaction effluent, - Figures 14 and 15 show a partial cross section substantially at each end of the reactor along AA and BB, and ~ 0 - Figure 16 shows a longitudinal section of the reactor.

In FIGS. 1a, 1b, 1c, and 1d, the same elements of the device according to the invention by the same references followed by the letters a, b, c and d.

By way of example, in the application of the apparatus of the invention to the synthesis of methanol (Figure la) a mixture mainly comprising hydrogen and carbon oxides are brought in through the inlet pipe the on the top of reactor 2a containing catalyst of the type of those described in the book "Applied Industrial Catalysis" (Volume 2, Chap 6, p226 and following).

The reactor 2a which is a vertical cylinder comprising an envelope 10 of cylindrical section and circular base closed at both ends by ellipsoid bottoms or preferably by hemispherical bottoms (30 and 31 ', 14 13 ~ 2S9 fig 16 ~ is divided into three compartments without internal communication, 201a, 202a and 203a, of increasing volumes respectively Vl <V2 <V3 by means of two flat, watertight internal walls (210a and 21la) which can be fixed for example by welding to the casing 10 and to funds 30 and 31 arranged, substantially parallel to the generator of reactor 2a.

Catalyst 11 was loaded from the upper bottom of the reactor into the various compartments. All of the sectional sections of the compartments fits into the circular base envelope 10.

The reaction fluid, previously conditioned from the point of view of pressure at 8 MPa and in terms of temperature around 250 ~ C is introduced into compartment 201a substantially parallel to the party wall by at least one distributor 20 pierced with vertices 12 (fig 8) generally dispersed around its outer wall facing the collector. In contact with catalyst 11 in the comparison timent, hydrogen combines with carbon oxides to give the methanol according to the equations:
CO + 2H2 ~ CH3 OH (1) COz + 3H2 ~ CH3 OH + H20 (2) Reactions (1) and (2) are exothermic and as the conversion progresses, the temperature of the fluid or of the effluent reaction-nel increases.

When the rise in the temperature of the reaction effluent reaches 20 to 60 ~ C which corresponds to a presence of approximately 1 to 3% volume of methanol in the gas, this is taken from 201a by at least one manifold 21 pierced with openings (fig 8) or with grid 12 and brought by the conduit 3a located in the lower part towards a means of transfer of heat 4a known per se, for example an external refrigerant, which significantly returns to its initial temperature at the time of entry into 201a. Instead of a heat exchange on 4a, it is possible to quench by means of introduction 4f of at least part of the fluid reaction or cold effluent on the pipe bringing the effluent to the next compartment.
B

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13 ~ 025 ~

Refrigerant 4a which can be either an air cooler or a preheating heat recovery unit for example all or part of the charging or producing hot water or pressurized steam, the gas mixture is brought back through line 5a to the top of reactor 2a where it is introduced by at least one distributor 22 into the compartment 202a symmetrically opposite compartment 201a.

When, due to the reaction, the gas temperature is again raised from 20 to 60 ~ C relative to its inlet temperature, the effluent reaction is again drawn off by at least one collector 23 in the lower part of the reactor, brought via line 6a, to the refrigerant 7a which reconditions it, again, to the initial optimal temperature.
From 7a, the fluid borrows the conduit 8a at the upper part of the reactor to reach compartment 203a of reactor 2a by at least a distributor 24.

At the outlet of 203a, the mixture which finally contains between 2 to 12% in methanol volumes is delivered by the collector 25 and by the conduit 9a in the lower part of the reactor to the condensing and purifying unit cation of synthesized alcohol.

According to this figure, the fluid and the reacting effluent are circulated crosswise substantially perpendicular to the generator of the reactor and parallel to the common wall.

The compartments 201a, 202a, 203a can be arranged side by side, with compartment 202a occupying the central position. This mini order stresses exerted by pressure differences on the party walls 210a, 21la.

A preferred arrangement is that the last compartment 203a (figla) occupies a central position with respect to the first two 201a and 202a.

Comparative studies have shown that it is this arrangement which is the most favorable from the point of view of the optimization of space.
useful available.

In the above description (fig la), the reactor 2a is arranged to vertical way.

When local conditions dictate it, for example, when the soil is spongy and not very resistant, the reactor 2 can be arranged horizontally according to another embodiment as indicated by the figure lb.

In this alternative, preferably, the conduits 1b, 3b, 5b, 6b, 8b and 9b are placed so that the circulation of the reaction fluid is made substantially parallel to the party wall and from top to low, which avoids the dangers of destabilization of the catalytic beds by blowing the catalyst grains.

IS In FIG. 1c illustrating another embodiment, there is shown a reaction system intended for the catalytic reforming of gasolines, which is endothermic. The diagram illustrates at the same time an example where the reaction fluid and effluent flow perpendicular to the walls 210c, 211c, in compartments 201 c and 202 c, and where they run parallel to these same walls in compartment 203c.

In the lc circuit, naphtha vapors circulate as well as recycled hydrogen. The mixture of gas and naphtha vapor is previously conditioned at about 0.5 to 3 MPa to about 500 to 530 ~ C.
In compartment 201 c of reactor 2c, the reforming catalyst which may be platinum deposited on an acid support and doped by various other noble metals, such as rhenium, subjects naphtha essen-dehydrogenation reactions which greatly lower the reaction fluid temperature, up to around 450 - 480 ~ C.
This fluid is then extracted from 201c to come through the conduit 3c on the outdoor oven 4c, known per se, which brings it again around 500 ~ C
The fluid is then sent through line 5c to compartment 202c.
In compartment 202c, to dehydrogenation reactions, come add molecule rearrangement reactions and lowering of temperature is much less important.

17 13 ~ 259 When this lowering reaches around 10 to 30 ~ C, the fluid is out of the second compartment 202 c and reheated again around 500 ~ C in the oven 7c.
The third compartment 203 c is practically isothermal. Indeed, at molecular dehydrogenation and rearrangement reactions came add hydrogenation reactions which are exothermic and whose heat of reaction practically compensates for that of reforming properly said.

The methods of the invention according to Figures la, lb and lc apply reactors whose different compartments can be connected by series of fason to constitute a succession of stages in the kinetic sense of word.

They also apply to multi-stage reactors, some of which compartments can be connected in parallel (figure ld) to form together either the first or the last reaction stage.

This particular embodiment can be advantageous in certain case, in particular in synthesis of ammonia.
Indeed, we know that we can currently operate this synthesis under relatively mild conditions (pressure around 10 MPa and temperature around 400 ~ C) and that under these conditions, it is no longer necessary to provide a double jacket to cool the wall outside of the reaction chamber.
However, it always arises for these reactors with an uncooled wall so-called "hot wall reactors" the problem of pressure losses due to high volume flow of gases through the catalytic bed.
Being able to halve the gas flow in places critics helps to get around this difficulty.
In FIG. 1d, the diagram of a reactor for synthesis has been represented.
of ammonia, produced according to the method of the invention.
A synthesis gas mixture containing approximately 25% nitrogen, 75%
of hydrogen, traces of ammonia and argon ( <5%) are introduced under about 10 MPa and at 350-400 ~ C in the ld conduit. The ld conduit is extended by two conduits ldl and ld2 which bring this gas into the two compartments 201dl and 201d2, advantageously of equal volumes and-equal sections, and arranged symmetrically to the axis of the 18 1 3 ~ 2 5 3 cylinder forming reaction volume.

Thanks to this paralleling, the volume of the first catalytic stage, although low compared to the volume flow rate of the synthesis gas, ultimately offers little resistance to gas passage.

At the outlet of the compartments in parallel 201 dl and 202 d2, the gas from synthesis contains approximately 4 to 7 ~ of ammonia and its temperature is high about 40 to 60 ~ C.
Through the 3dl and 3d2 conduits the gas flow rates lead to the 3d conduit which leads to the 4d heat recovery exchanger.

At the outlet of the exchanger 4d, the gases cooled to the op-timale of approximately 350-400 ~ C are brought by the conduit 5 d on the com-central part 202 d of reactor 2d.

The effluent gases from reactor 2d, which contain approximately 8 to 14% by volume lumines of ammonia and which are approximately 400-450 ~ and below about 10 MPa, are sent through line 6d to the packaging unit and ammonia recovery located downstream of the reaction section.

In the reactors thus described, (fig la, lb, lc) the partition walls 210-211, if they are discharged from the weight of the catalyst which is directly on the wall of the enclosure, however, have to resist general thrust due to pressure difference between compartments adjoining 201-203 on the one hand, 203-202 on the other.

These pressure differences which are due to the pressure drop across catalytic beds and heat transfer devices are 0.1 to 0.4 MPa and can even reach lMPa in the event that reheating furnaces intervene as with reforming by example.

In the example of the reactor for methanol synthesis represented by the figure la, the wall 210a which is for example 3200 mm wide and 20 mm thick enough to withstand a pressure difference of 0.3 MPa.

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19 13 402 ~

When using a support system parallel to the plane of this wall we can use beams of the HEM 400 type distributed by example every 500 mm (figure 2).

With a perpendicular support system, you can use by example, tie rods 25 mm in diameter, arranged in a mesh square with a side of 500 mm, the tie rods 27 being connected on the one hand to the partition 210, on the other hand to the wall of the reaction vessel 10 (figure 3).
The flat wall with its relatively bulky support systems and difficult to install can be replaced by a simple wall but having a specially studied shape allowing it to be able to resist alone against pressure. When we adopt a freestanding form, we 15 may in particular use profiles 28 of the same thickness, for example as that of the flat wall 210 (20 mm) of the type indicated in FIG. 4 and whose height for example can be 300 mm and the pitch of 395 mm.

Figures 5 and 6 show other self-supporting forms of 20 the invention with convexity and concavity oriented towards the compartments 201 and 202. The combination of these various forms can also be meet. These forms are preferred to those presented in the figure 4 because they facilitate the connection between these walls and the wall cylindrical of the reactor.

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13 ~ 253 The walls 210, 211 are cylinder sectors whose generators - are substantially parallel to the generator of the reaction vessel and whose bases are arcs of circle whose radius is between 0.1 and 100 times, preferably between 0.5 and 50 times, that of the enclosure reactive.

In the reactors according to the invention, the reaction fluids circulate transversely in a way perpendicular to the generator of the enclosure.
To this end, distributors 20, 22, 24 and collectors 21, 23, 25 are preferably consisting of pipes substantially parallel to this generator, which have generally dispersed openings 12 around their walls towards the catalytic bed.

Preferably, the section of the distribution pipes 20, 22, 24 and / or collection 21, 23, 25 can adopt one of the forms shown on the figures, either a circular section (fig 7), or a sector formed at the location of the junction between the reaction wall and the terraced separation and closed by a plan (fig 8) or by a piece of circular base cylinder (Fig 9); the circulation of fluids takes place then substantially parallel to the party walls.

When the total section of distributors or that of collectors represents more than 10%, preferably more than 20% of that reserved to the catalyst, distributors 20, 22, 24 and collectors 21, 23, 25 are preferably made of several pipes (fig 10, 11 and 12) substantially parallel and distributed along the partition wall 210 adjoining and where appropriate along the wall part of the enclosure reaction girdle facing it 211; circulation takes place then substantially perpendicular to the party walls.

These different distribution pipes 20a, 20b, 20c ... of the first crossed compartment, 22a, 22b, 22c, ... of the second compartment crossed and 24a, 24b, 24c of the third compartment crossed as well as the different collection pipes 21a, 21b, 21c ..., 23a, 23b, 23c ..., 25 a, 25 b, 25c respectively of the first, second and third compartment can be in the form of circular sectors (Fig 10) or polygons for example of triangle (fig 12), square or rectangle (fig 11) This same figure 11 illustrates the case where the number of distributors 24 is less than the number of collectors 25 ... We could have just as well build a reactor where the number of collectors is less than the number distributors.

FIG. 13 represents another embodiment of the distributors ~ and collectors either in an arc ~ 0, 22 against the envelope, or planes 21, 23, 24, 25 against the party walls 210 and 211;

According to these various embodiments, a larger section of the 12 openings compensates for the reduced number of distributors or collectors.
The openings 12 for the introduction and collection of fluids can have any shape, circular for example, and they have their area proportional to the average distance corresponding to each distributor-collector couple so as to minimize the passages preferred gaseous fluids.

As shown in Figures 14, 15 and 16, illustrating a mode of distribution and collection means, leads it of Figure la is substantially located at one of the ends 30 of the reactor or of the first compartment 201a while the conduit 3a outlet is substantially located at the other end 31 of the reactor or first compartment. The section of the distribution pipe, for example 20, in compartment 201a at the end 30 (fig 14 section AA) is greater than the distribution section 20 at the level end 31 (fig 15 section BB) while the cross-section of the reading 21 at the end 30 is lower than that of the collection pipe 21 at the end 31. The same is true for the sections of other distribution pipes 22, 24 and collection pipes 23, 25 in the other compartments (fig 14, 15). According to Figure 16 illustrating more particularly this embodiment, the walls of the distri-scorers 20 and collector 21 facing the catalytic bed may include sections (grids with holes 12 for example) substantially pa-parallel to the generator which are offset from each other in the same direction so that the thickness of the bed crossed by the fluids is the same all along the reactor and that said walls are generally oblique to the generator.

The catalyst loading operations can generally be carried out LEMENT by at least one opening 32 on the upper bottom of the reactor and preferably by at least one opening per compartment. In the case of horizontal reactors with vertical dividing walls 210b and 211b (figure lb), loading can be done through openings generally arranged on the reactor casing to the right of each compartment.

Unloading is generally carried out from below by at least one discharge opening 33 and preferably by at least one opening in each compartment. These loading and unloading operations are easy to carry out and do not immobilize the reactor for a long time.

Reactor walls (envelope walls and / or party walls) can be thermally insulated. An intermediate fluid can be introduced 23,134,0259 diary, de-heating or cooling which can possibly circ culer in the partitions in particular in the dividing walls of compar-adjacent buildings.

In the figures above, only a three-reactor is shown compartments and two means of thermal transfer for a reason of clarity. It is obvious that one can build according to the invention a reactor with a plurality of compartments for example from 3 to 10 and intermediate heat transfer means.

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Claims (46)

1. Process for carrying out under pressure chemical reactions in a cylindrical reaction zone based on circular section comprising at least two compartments, a first and a second, each containing at least in part at least one solid catalyst, process in which a reaction fluid is introduced into the first compartment, said fluid is circulated reaction in said first compartment, a first reaction effluent from said first compartment, heat exchange outside the reaction zone between said first reaction effluent to enter the second compartment and a heat exchange medium external, then introducing said first effluent having exchanged heat in said second compartment, circulates said first effluent in said second compartment and a desired mixture is recovered, said zone reaction being elongated and having a envelope with at least one generator, said envelope defining a closed section lying in a plane cutting said generator, process in which:
- circulating said reaction fluid in said first compartment transversely and so substantially perpendicular to said generator, and we make circulating said first reaction effluent in said second compartment transversely and so substantially perpendicular to said generator, - said compartments being of elongated shape according to said generator and being waterproof, - said compartments being adjacent to each other, and - said compartments forming a group having a wall which is tightly connected to said envelope. 2. The method of claim 1, wherein said reaction fluid includes hydrogen and oxide carbon. 3. The method of claim 2, wherein the area more than two compartments, and in which:
- each of said compartments is adjacent to one or two compartments, and - each group of two adjacent compartments having a common wall which is tightly connected to said envelope. 4. The method of claim 3, wherein said reaction zone includes three compartments, and in which:
- when circulating said first effluent in said second compartment we recover it in the form of a second reaction effluent from said second compartment, and - after having reconditioned said second effluent reaction outside the reaction zone to a optimal temperature it is reintroduced in a third compartment from which it is permanently recovered from the lower part of the reaction zone, in the form of desired mixture. 5. The method of claim 1, wherein introduces the reaction fluid substantially at a level first end of the reaction zone, we do circulate the reaction fluid in the first compartment having a section distribution area gradually decreasing, and the reaction effluent is recovered at level of the second end of the reaction zone which is of increasing section. 6. Method according to claim 1 or 2, wherein heat exchange by mixing them reaction effluents with relatively cold gas. 7. The method of claim 1 or 2, wherein circulates said fluid and said first effluent reaction in said compartments so that the total course in the reaction zone is less than twice the length L of said reaction zone. 8. The method of claim 1 or 2, wherein circulates the reaction fluid and said first reaction effluent substantially parallel to said party wall. 9. The method of claim 1 or 2, wherein circulates the reaction fluid and said first reaction effluent substantially perpendicularly to said party wall. 10. The method of claim 1 or 2, wherein the reaction zone is horizontal. 11. The method of claim 1 or 2, wherein the reaction zone is vertical. 12. The method of claim 7, wherein one does circulate the reaction fluid and said first effluent reaction from top to bottom in said compartments. 13. The method of claim 1 or 2, wherein the reaction zone includes at least three compartments and in which the reaction fluid is circulated in parallel in two compartments. 14. The method of claim 3, wherein one does circulate the reaction fluid then said first effluent reaction in a succession of volume compartments bigger and bigger. 15. The method of claim 3, wherein one does circulate the reaction fluid or said first effluent reaction in each of the compartments connected in series. 16. The method of claim 1, 2, 3, 4, 5, 14 or 15, in which the velocity of the fluids in the compartments is between 1m / s and 200 / ms. 17. Method according to claim 1, in which:
- the reaction zone includes at least three compartments, a first compartment, a last compartment and at least one intermediate compartment, and in which, - the reaction fluid is introduced into said first compartment by means of at least one distribution area, - reaction effluents are recovered from each of the said first and said at least one intermediate compartment, these reaction effluents being introduced into at least one subsequent compartment by means of at least one zone of distribution, and each of said reaction effluents is recovered in at least one collection area. 18. The method of claim 1, wherein said said chemical reactions include the reaction of hydrogen and carbon oxides to form methanol, and in which said reaction fluid contains hydrogen and carbon oxides. 19. The method of claim 1, wherein said party wall is parallel to said generator. 20. The method of claim 1, wherein said party wall is oblique to the generator. 21. Process for carrying out reactions under pressure chemicals in a cylindrical reaction zone based on circular section comprising at least two compartments, a first and a second, each containing at least part at least one solid catalyst, process in which introduces a reaction fluid into at least one compartment, circulating said reaction fluid in said first compartment, we recover a first effluent reaction of said compartment, heat is exchanged at outside the reaction zone between said first effluent to enter at least one subsequent compartment and an external heat exchange medium, then introduces said first effluent having exchanged heat in said at least one subsequent compartment, circulates said first effluent in the compartment subsequent and a second reaction effluent is recovered of said subsequent compartment, said reaction zone being of elongated shape and comprising an envelope with at minus a generator, said envelope defining a closed section lying in a plane cutting said generator, process in which:
- Introducing the reaction fluid into said at least one compartment by means of at least one distribution area, and said first reaction effluent is introduced into said at least one subsequent compartment by means of at least at least one other distribution zone, said reaction fluid and said first reaction effluent flowing in said compartments perpendicular to said generator, said compartments being sealed and elongated shape, each of said compartments being adjacent at least one other compartment, each group of two adjacent compartments with a common wall or which is tightly connected to said envelope, and - each reaction effluent is recovered in at least one collector area. 22. The method of claim 17, wherein said reaction fluid is introduced into said reaction zone at one end of this reaction zone and flows across from said section distribution area progressively decreasing from said first end of the reaction zone towards a second end of this reaction zone, said first reaction effluent being unloaded in a section collection area gradually increasing, said first reaction effluent being recovered at said second end of said reaction zone. 23. Apparatus for carrying out reactions under pressure chemicals including:
- an elongated reactor capable of containing at least minus a catalyst, having a substantially envelope cylindrical defined by at least one generator and having a first end and a second end waterproof, - at least two adjacent compartments, contained in said elongated reactor along said generator, each group of two adjacent compartments comprising a dividing or common wall, each compartment comprising in addition at least one means for entering the reaction fluid or of the reaction effluent in said compartment and at minus a means of leaving the reaction effluent which has passed through said compartment, said means of entry and outlet being in communication with the outside of the reactor through said envelope, characterized in that:
- said compartments are waterproof, said wall adjoining or common being either substantially parallel to the generator is substantially oblique to it and in this that the reactor includes:
- at least one means of distribution in each compartment suitable for transversely distributing in each compartment the reaction fluid or the reaction effluent from substantially perpendicular to said generator and connected to said input means, - at least one means of collecting the reaction effluent circulating in each compartment, this means of collection being connected to said outlet means of said compartment, and - at least one heat transfer means located at the outside of the reactor interposed between said means of outlet of the reaction effluent from one of the compartments and the means of entry of the reaction effluent into the next compartment. 24. The apparatus of claim 23, wherein said compartments have sectional sections which fit into the substantially cylindrical shell of the reactor. 25. Apparatus according to claim 23 or 24 wherein the reactor shell has a circular cross-section base. 26. Apparatus according to claim 23 or 24 wherein said party wall comprises planar panels supported. 27. Apparatus according to claim 23 or 24 wherein said party wall comprises shaped panels freestanding. 28. The apparatus of claim 27, wherein the self-supporting curved panels have a base either in an arc whose radius is between 0.1 and 100 times that of the reactor either in portion of curves quadratic. 29. Apparatus according to claim 23 or 24 wherein said distribution means and said collection means are arranged substantially parallel to said generator, in each compartment. 30. Apparatus according to claim 23 or 24 wherein said input and output means are respectively located substantially at the first end and the second end of the reactor, characterized in that the section of the distribution means at said level first end is greater than the section of the means of distribution at the second end and in that the collection means section at the first level end is less than that of the collection means at level of the second end. 31. The apparatus of claim 23 or 24, wherein said distribution and collection means include either at least one distribution and collection section substantially parallel to said generator or at least a distribution or collection section substantially oblique to said generator, each of these sections being offset from each other in the same direction all along the reactor. 32. The apparatus of claim 23 or 24, wherein said distribution means and said collection means have a plurality of openings arranged along of said means and the respective sections of which are substantially proportional to the distance between said distribution means and said collection means. 33. The apparatus of claim 23 or 24, wherein the reactor is horizontal and has at least one wall semi-vertical. 34. Apparatus according to claim 23 or 24, comprising means for introducing cold gases disposed at the outlet reaction effluent from a compartment before entering in the subsequent compartment. 35. The apparatus of claim 24, wherein the reactor shell has a circular cross-section base. 36. The apparatus of claim 35, wherein said dividing wall includes supported flat panels. 37. The apparatus of claim 35, wherein said dividing wall includes self-supporting panels. 38. The apparatus of claim 37, wherein the self-supporting curved panels have a base either in an arc whose radius is between 0.1 and 100 times that of the reactor either in portion of curves quadratic. 39. The apparatus of claim 38, wherein said distribution means and said collection means are arranged substantially parallel to said generator, in each compartment. 40. The apparatus of claim 39, wherein said input and output means are located respectively substantially at the first end and the second end of the reactor, characterized in that the section of the distribution means at said level first end is greater than the section of the means of distribution at the second end and in that the collection means section at the first level end is less than that of the collection means at level of the second end. 41. The apparatus of claim 40, wherein said distribution means and said collection means comprise either at minus a distribution and collection section substantially parallel to said generator or at least a distribution or collection section substantially oblique to said generator, each of these sections being offset from each other in the same direction all along the reactor. 42. The apparatus of claim 41, wherein said distribution means and said collection means comprise a plurality of openings disposed along said means and whose respective sections are substantially proportional to the distance between said distribution means and said collection means. 43. The apparatus of claim 42, wherein the reactor is horizontal and has at least one wall semi-vertical. 44. Apparatus according to claim 43, comprising means for introducing cold gases arranged at the outlet of the reaction effluent of a compartment before it enters in the subsequent compartment. 45- Use of the apparatus according to claim 23, 24, 25, 36, 37, 38, 39, 40, 41, 42, 43 or 44, for the synthesis of ammonia from hydrogen and nitrogen or for the synthesis of methanol or homologous alcohols higher from hydrogen and carbon oxides or for catalytic reforming of gasolines. 46. Use of the method according to claim 1, 2, 3, 4, 5, 17, 18, 19, 20, 21 or 22, for the synthesis of ammonia from of hydrogen and nitrogen or for the synthesis of methanol or higher homologous alcohols from hydrogen and of carbon oxides or for the catalytic reforming of essences.